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The purpose of the CIOC

What is the purpose of the CIOC?

The Comet ISON Observing Campaign, or CIOC, was established at the request of NASA to help encourage, facilitate and coordinate a broad observing campaign comprising as many NASA observatories as possible, and all other observatories that may wish to join in. This means that we are not taking observations ourselves (though many of the individuals on the CIOC Team are involved in their own observing programs), but instead are tasked with raising awareness of the potentially rare opportunity that Comet ISON presents us with, and providing observatory teams with information and advice regarding programs they may wish to offer or undertake.

The observatories include both space and ground-based observatories, and while we are only tasked directly with coordinating NASA-backed or NASA-funded programs, we are open and available to assist with any of our international partners who wish to join in the Campaign. You can read more about this on our CIOC Participation page.

Why do we care about Comet ISON? What's so special?

We are frequently asked why Comet ISON so special, particularly when we hear all the time about different comets in the sky, and there are several facets to the answer.

Comet ISON is a Sungrazing Comet, which basically means it has an orbit that brings it very close to the Sun. Such comets are actually quite common, with the SOHO satellite having discovered over 2,500 such objects since it began operations in 1996! (These discoveries were made by the Sungrazing Comets citizen science project.) However, nearly all of SOHO's sungrazers are tiny object, only visible for a few short hours prior to being vaporized in the Sun's extended outer atmosphere. It is very rare that we get to see a large Sungrazing comet such as Comet ISON. The last instance of a big Sungrazer was Comet C/2011 W3 (Lovejoy), which spectacularly grazed through the Sun's outer atmosphere in December 2011. But even with Comet Lovejoy, we only had two weeks warning of its close passage to the Sun -- enough time to get some amazing spacecraft images planned but certainly not enough to orchestrate a major campaign.

But what's the big deal about Sungrazers? The passage of a comet so close to the Sun results in the comet's nucleus being exposed to far more intense gravitational stress and solar radiation that comets typically receive. As a consequence, gas and dust production from the comet can be extreme, and elements in the comet's nucleus that are normally less volatile get sublimated (melted/vaporized) by the intense solar radiation. With the correct types of observations, we can detect the sublimation of these elements and learn more about the structure and composition of comets.

Another interesting facet of Comet ISON is that it appears to be a dynamically new comet, fresh from the Oort Cloud. This means it has probably never been through our solar system, and has never been subjected to the melting effects of solar radiation. It's a truly pristine example of early solar system material, and thus we are particularly eager to see the combined result of a "raw" piece of solar system material being subjected to the Sun's outer atmosphere!

Finally, Comet ISON was discovered in September 2012 -- more than a year before it is due to pass by the Sun in November 2013. This provides us the very long lead-time we desire to be able to put together an observing campaign as ambitious as the CIOC. We hope that with good planning and preparation, and a big slice of good luck in the form of a large, bright comet, we will be able to make a historic set of observations.

Blog archive

Image of the Week

Every week, a new image related to Comet ISON!

This week: The Final Nail in the Coffin? When ground-based observers came up empty-handed in the hunt for ISON's remains, we turned to the Hubble Telescope to see if its ultra-powerful instruments could find anything...Earlier picks can be found in the ISON Image of the Week Archives. Note that this feature will become monthly, instead of weekly, in 2014.